It is well known that, for a large heavy-duty all-terrain engineering machinery, the traveling stability of a chassis thereof directly affects an operation performance of the whole machinery. In addition to a chassis power system, a suspension system is also a critical factor affecting the traveling stability.
Taking an all-terrain crane as an example, a suspension system for the chassis thereof generally employs a conventional rigid axle. The suspension system is mainly divided into two types, including a dependent suspension system and an independent suspension system, according to the structural feature of a guide mechanism. In the dependent suspension system, a left wheel and a right wheel are mounted on one integral rigid axle or an axle housing of an non-divided drive axle; however, in the independent suspension system, the left wheel and the right wheel are not connected by one rigid beam or a non-divided axle, but are independently connected to a frame or a body of the crane, thereby forming a divided axle. According to the structural features of the dependent suspension system and the independent suspension system, the suspension system for the chassis of the conventional all-terrain crane is gradually transformed into the independent suspension system.
Reference is made to FIGS. 1 and 2, FIG. 1 is a schematic view showing the structure of a typical independent suspension system in the conventional technology, and FIG. 2 is a schematic side view of FIG. 1.
As shown in the figures, the suspension system has a divided axle, which transmits power to wheel hubs at two sides via two universal drive shafts 10 respectively. A guide sleeve of a suspension oil cylinder 20 is fixed on a frame 30, a lower end of a piston rod is connected to the wheel hub of a wheel, to support the frame and buffer the frame vibration caused by jumping of the axle. A main speed reducer 40 is fixedly connected to the frame, and is connected to the wheel hubs via the universal drive shafts, to realize the transmission of force. A rocker arm 50 of a steering mechanism is mounted on the guide sleeve of the suspension oil cylinder, a rolling bearing is installed between the rocker arm 50 and the guide sleeve, thus the rocker arm 50 is rotatable with respect to the guide sleeve. When the wheel turns, a booster oil cylinder drives the steering rocker arm to rotate, the steering rocker arm drives a trapezoidal knuckle arm fixedly connected to the wheel hub to rotate, thus realizing the steering of the wheels.
However, due to the limitation of its structure, the conventional independent suspension system has the following disadvantages.
Firstly, a lateral surface of the guide sleeve of each of the suspension oil cylinders is connected to the frame, the lower end of each of the piston rods is connected to the wheel hub of the wheel, and the weight of the body and support reactions applied to tires by the ground both act on the suspension oil cylinders, thus the suspension oil cylinders are subjected to a large force and are apt to be wore, which may adversely affect the service life thereof.
Secondly, the whole steering mechanism is mounted above the main speed reducer, and a steering knuckle arm is fixed at an outer side of the guide sleeve of the oil cylinder, thus a minimum clearance between the main speed reducer and the ground cannot be effectively controlled, which leads to a poor traveling trafficability.
In view of this, it is urgent to optimize the design of the independent suspension system in the conventional engineering machinery, to effectively improve a force bearing state of the suspension oil cylinder and to avoid the abrasion that may adversely affect the operational performance and the service life.